Fishes

15 pages, 4881 KB

Open AccessArticle

Comparative Demography of Five Holocentridae Species from American Samoa

by Cassandra Pardee, Domingo Ochavillo and Brett M. Taylor

Fishes 2025, 10(11), 596; https://doi.org/10.3390/fishes10110596 - 20 Nov 2025

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This study provides the first insights into the age-based life histories of five Holocentridae species (soldierfish and squirrelfish) from American Samoa: Myripristis amaena, M. berndti, M. murdjan, Sargocentron spiniferum, and S. tiere. Examination of sagittal otoliths revealed that all [...] Read more.

This study provides the first insights into the age-based life histories of five Holocentridae species (soldierfish and squirrelfish) from American Samoa: Myripristis amaena, M. berndti, M. murdjan, Sargocentron spiniferum, and S. tiere. Examination of sagittal otoliths revealed that all five species exhibited long lifespans with maximum estimated ages of 17 to 40 years. The Holocentridae complex exhibited a consistent slow-turnover strategy characterized by long lifespans, asymptotic growth profiles, and low rates of instantaneous total mortality (Z ≤ 0.20 yr⁻¹). Reproductive information, derived from histological examination of gonads, indicated that the onset of maturity for all five species occurred later than is typical for many demersal reef fishes. This pattern was exemplified by female S. tiere, which reached 50% maturity at age 6.5 years. The size at maturity occurred between 65% and 91% of asymptotic length for all species. All species demonstrated a primary spawning season during the austral summer (October–February). Full article

(This article belongs to the Special Issue Age Determination of Aquatic Animals)

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17 pages, 3265 KB

Open AccessArticle

Fish Diversity and Spatial Patterns in the Upper Yangtze River National Nature Reserve for Rare and Endemic Fish Based on Environmental DNA (eDNA) Technology

by Xiaohan Dong, Jiaxin Huang, Zongqiang Qi, Ziwei Wang, Qing Zuo and Yanjun Shen

Fishes 2025, 10(11), 595; https://doi.org/10.3390/fishes10110595 - 19 Nov 2025

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Abstract

The Upper Yangtze River National Nature Reserve for Rare and Endemic Fish is a critical sanctuary facing increasing pressure from hydropower development. To assess its current ecological state, we employed environmental DNA (eDNA) metabarcoding on 48 water samples collected from 16 transects in [...] Read more.

The Upper Yangtze River National Nature Reserve for Rare and Endemic Fish is a critical sanctuary facing increasing pressure from hydropower development. To assess its current ecological state, we employed environmental DNA (eDNA) metabarcoding on 48 water samples collected from 16 transects in August 2024. Our analysis identified 93 fish species from 3 orders, 13 families, and 67 genera, of which 89 were consistent with historical records. The Cyprinidae family was dominant. The fish community was predominantly characterized by slow-flowing, benthic, omnivorous, and migratory taxa that lay adhesive eggs, with key life-history traits including a sexual maturity age of 1–4 years and a length at first maturity under 20 cm. Spatially, species richness was highest in the Chishui River (64 species), followed by the Minjiang River (61 species). While alpha diversity was largely consistent across most rivers (except the Minjiang), beta diversity analysis revealed significant compositional differences among basins (PERMANOVA, R² = 0.2747, p = 0.001). Notably, the Chishui River supported not only the highest richness but also a distinct community structure. In summary, this study provides a systematic current status assessment of the reserve’s fish resources, revealing significant spatial heterogeneity, Our findings underscore the potential impacts of dam construction and offer a scientific basis for informing effective conservation strategies. Full article

(This article belongs to the Special Issue Mapping and Monitoring Aquatic Biodiversity in Hotspot Habitat Areas Using Environmental DNA (eDNA))

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20 pages, 2479 KB

Open AccessArticle

Global Empirical Assessment of Marine Heatwaves’ Impacts on Fisheries Production and Economic Value

by Arturo Yañez-Arenas, Daniel B. Lluch-Cota, Jesús Ernesto Arias-González, R. Zehra Zaidi and Salvador E. Lluch-Cota

Fishes 2025, 10(11), 594; https://doi.org/10.3390/fishes10110594 - 19 Nov 2025

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Abstract

Marine heatwaves (MHWs) have become increasingly frequent and intense, raising concerns about their impacts on fisheries production and economic value. We present a global assessment of MHW-related impacts across 2088 marine fisheries from 1985 to 2022. Using high-resolution satellite data and standardized catch [...] Read more.

Marine heatwaves (MHWs) have become increasingly frequent and intense, raising concerns about their impacts on fisheries production and economic value. We present a global assessment of MHW-related impacts across 2088 marine fisheries from 1985 to 2022. Using high-resolution satellite data and standardized catch production and catch value, we identified significant reductions in catch and ex-vessel value during years of elevated thermal stress. A total of 322 fisheries (15%) showed statistically significant declines during years with high MHW activity, with regional disparities indicating that the Northeast Atlantic and Southeast Pacific experienced the highest cumulative losses, while country ranking highlighted Norway, China, Japan, and Peru as the most affected. Estimated accumulated global losses since 1985 exceeded 5.6 million tonnes and USD 6.6 billion (2005 USD equivalents), nearly 40% of which occurred during 2013–2022. These findings emphasize the need to incorporate extreme thermal events into fisheries risk assessments and adaptation strategies, especially in highly productive or strategic regions. Full article

(This article belongs to the Special Issue Effects of Climate Change on Marine Fisheries)

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16 pages, 1126 KB

Open AccessArticle

Effects of Astragalus Polysaccharide and Isatis indigotica Extract Synergy on the Antioxidant Status, Inflammation, Autophagy, Apoptosis, and Intestinal Health of Larimichthys crocea Juveniles

by Zhichu Chen, Chao Zeng, Ai Wang, Huiyu Wang, Xin Zhi, Zhengbang Chen, Huiyuan Lv, Qiong Qi, Pan Wang, Jianchun Shao and Xinhua Chen

Fishes 2025, 10(11), 593; https://doi.org/10.3390/fishes10110593 - 19 Nov 2025

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Abstract

This research aimed to examine the combined influence of Astragalus polysaccharide (APS) and Isatis indigotica extract (IIE) dietary supplements on oxidative-inflammatory status, cellular homeostasis, and intestinal integrity in large yellow croaker (Larimichthys crocea). Three replicates of experimental fish (n = 160) [...] Read more.

This research aimed to examine the combined influence of Astragalus polysaccharide (APS) and Isatis indigotica extract (IIE) dietary supplements on oxidative-inflammatory status, cellular homeostasis, and intestinal integrity in large yellow croaker (Larimichthys crocea). Three replicates of experimental fish (n = 160) received one of five dietary regimens: a basal control (CON) diet, the CON diet containing 0.1% APS (AP), and the AP diet supplemented with 0.05%, 0.1%, and 0.15% IIE (AI1, AI2, and AI3) for 8 weeks. The combined supplements, particularly in the AI2 group, significantly improved intestinal morphology and enhanced the activities of key digestive enzymes. Gene expression analysis revealed that the APS-IIE combination consistently upregulated the intestinal mRNA abundance of major tight junction proteins (CLDN4, OCLN, ZO1, ZO2) compared to the CON or AP groups. Liver antioxidant capacity was strengthened (enhanced CAT capacity), as evidenced by a significant reduction in lipid peroxidation (MDA) levels. In the head kidney, the combination downregulated the expression of pro-inflammatory cytokines (IL8, TNF) and toll-like receptors (TLR1, TLR2, TLR5), and promoted the expression of anti-inflammatory cytokines (IL10, TGFB1). Furthermore, dietary supplementation modulated the crosstalk between autophagy and apoptosis, indicated by altered expression of key marker genes (e.g., increased MAP1LC3B and decreased CASP3/8/9). In conclusion, the simultaneous inclusion of APS and IIE in diets promotes intestinal health, strengthens antioxidant status, and alleviates inflammatory responses, with the 0.1% APS + 0.1% IIE (AI2) formulation demonstrating the most pronounced benefits. Full article

(This article belongs to the Special Issue Advances in the Immunology of Aquatic Animals)

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20 pages, 2397 KB

Open AccessArticle

IMM-DeepSort: An Adaptive Multi-Model Kalman Framework for Robust Multi-Fish Tracking in Underwater Environments

by Ying Yu, Yan Li and Shuo Li

Fishes 2025, 10(11), 592; https://doi.org/10.3390/fishes10110592 - 18 Nov 2025

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Abstract

Multi-object tracking (MOT) is a critical task in computer vision, with widespread applications in intelligent surveillance, behavior analysis, autonomous navigation, and marine ecological monitoring. In particular, accurate tracking of underwater fish plays a significant role in scientific fishery management, biodiversity assessment, and behavioral [...] Read more.

Multi-object tracking (MOT) is a critical task in computer vision, with widespread applications in intelligent surveillance, behavior analysis, autonomous navigation, and marine ecological monitoring. In particular, accurate tracking of underwater fish plays a significant role in scientific fishery management, biodiversity assessment, and behavioral analysis of marine species. However, MOT remains particularly challenging due to low visibility, frequent occlusions, and the highly non-linear, burst-like motion of fish. To address these challenges, this paper proposes an improved tracking framework that integrates Interacting Multiple Model Kalman Filtering (IMM-KF) into DeepSORT, forming a self-adaptive multi-object tracking algorithm tailored for underwater fish tracking. First, a lightweight YOLOv8n (You Only Look Once v8 nano) detector is employed for target localization, chosen for its balance between detection accuracy and real-time efficiency in resource-constrained underwater scenarios. The tracking stage incorporates two complementary motion models—Constant Velocity (CV) for regular cruising and Constant Acceleration (CA) for rapid burst swimming. The IMM mechanism dynamically evaluates the posterior probability of each model given the observations, adaptively selecting and fusing predictions to maintain both responsiveness and stability. The proposed method is evaluated on a real-world underwater fish dataset collected from the East China Sea, comprising 19 species of marine fish annotated in YOLO format. Experimental results show that the IMM-DeepSORT framework outperforms the original DeepSORT in terms of MOTA, MOTP, and IDF1. In particular, it significantly reduces false matches and improves tracking continuity, demonstrating the method’s effectiveness and reliability in complex underwater multi-target tracking scenarios. Full article

(This article belongs to the Special Issue Technology for Fish and Fishery Monitoring)

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17 pages, 1504 KB

Open AccessArticle

Polycyclic Aromatic Hydrocarbons in Seafood: Occurrence, Trophic Bioaccumulation, and Human Health Risks

by Fabíola Helena dos Santos Fogaça, Pamella Talita da Silva Melo, Carlos German Massone, Renato da Silva Carreira, Leonardo Rocha Vidal Ramos and João Paulo Machado Torres

Fishes 2025, 10(11), 591; https://doi.org/10.3390/fishes10110591 - 18 Nov 2025

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Abstract

Polycyclic aromatic hydrocarbons (PAHs) can enter the human body through the consumption of contaminated food, particularly seafood, which can bioaccumulate these toxic compounds. This study evaluated PAH contamination levels in fish, crabs, and shellfish from the Parnaiba River estuary following the 2019 oil [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) can enter the human body through the consumption of contaminated food, particularly seafood, which can bioaccumulate these toxic compounds. This study evaluated PAH contamination levels in fish, crabs, and shellfish from the Parnaiba River estuary following the 2019 oil spill that impacted over 3000 km of Brazil’s northeastern coastline with weathered, heavy crude. The results showed that PAH concentrations in 2019 were approximately 50% higher than those detected in 2021, indicating an acute contamination event linked to the spill. Among the sampled organisms, crabs had the lowest PAH levels, followed by shellfish with intermediate contamination levels, and fish with the highest concentrations. PAH profiles varied by species: shellfish were dominated by high-molecular-weight (HMW) compounds typical of pyrogenic sources; fish were primarily contaminated with low-molecular-weight (LMW) PAHs associated with crude oil; and crabs exhibited a balanced mix of both. Toxicity equivalency analysis revealed the presence of benzo[a]pyrene (BaP) only in 2019 shellfish samples, while BaP contamination was found in both fish and shellfish in 2021. Some samples exceeded regulatory limits for indeno[1,2,3-cd]pyrene. Mollusks collected during the 2021 dry season presented BaP and benzo[k]fluoranthene levels above the threshold of concern. These findings demonstrate the acute impact of the oil spill, characterized by a predominance of LMW PAHs, as well as a residual contamination pattern in 2021, likely associated with pyrogenic sources and driven by environmental degradation processes. This study also indicates that although overall carcinogenic PAH levels decreased, some carcinogenic PAHs continue to exceed legal limits in fish and shellfish samples, even 2 years after the oil spill. This work highlights the need for long-term monitoring and reinforces the importance of including food safety in environmental impact assessments, especially in vulnerable fishing communities. Full article

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23 pages, 5780 KB

Open AccessArticle

Sediment Deposition Impacts on Fish Migration in Vertical Slot Fishways

by Zihao Ning, Jie Chen, Changbo Jiang, Yihan Liao, Tianshun Ding, Yulin Chen, Bin Deng and Wenkang Meng

Fishes 2025, 10(11), 590; https://doi.org/10.3390/fishes10110590 - 17 Nov 2025

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Abstract

Vertical slot fishways represent critical ecological migration facilitation structures and have been globally implemented to restore fish passage. However, most studies to date focus primarily on fishway hydraulics and fish behavior, with limited investigation into sediment deposition effects that may compromise functionality. To [...] Read more.

Vertical slot fishways represent critical ecological migration facilitation structures and have been globally implemented to restore fish passage. However, most studies to date focus primarily on fishway hydraulics and fish behavior, with limited investigation into sediment deposition effects that may compromise functionality. To address this gap, we integrated physical modeling and numerical simulations to systematically analyze sediment deposition in a vertical slot fishway and its impacts on common carp upstream migration. Results indicate that sediment deposition raised fish vertical swimming positions by an average of 5.0 cm, thereby reducing pool activity space by 5.2–20.2%, altering flow patterns, and disrupting carp bottom-migration behavior. Consequently, carp exhibited increased exploratory behavior and directional uncertainty. Moreover, sediment-induced vertical vortices elevated fish energy consumption, decreasing upstream migration success from 89% to 48%. Multiple linear regression confirmed that average sediment deposition height significantly affects both migration rate and vertical swimming positions, whereas mean deposition slope demonstrates negligible influence. This study elucidates the multifaceted impacts of sediment deposition on fishway efficacy, providing a scientific basis for optimizing designs to enhance migration success and long-term functionality. Full article

(This article belongs to the Section Biology and Ecology)

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18 pages, 2535 KB

Open AccessArticle

Assessment of Exploited Stock and Management Implications of Kingfish (Scomberomorus commerson) in the Omani Waters

by Usama Aladawi, Samroz Majeed, Ibrahim Al-Anboori and S. M. Nurul Amin

Fishes 2025, 10(11), 589; https://doi.org/10.3390/fishes10110589 - 15 Nov 2025

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Abstract

The high demand and economic value of kingfish (Scomberomorus commerson) have led to intensive fishing of this species in the Omani waters. The increased fishing pressure has made the fishery vulnerable; hence, information on the current stock status is essential for [...] Read more.

The high demand and economic value of kingfish (Scomberomorus commerson) have led to intensive fishing of this species in the Omani waters. The increased fishing pressure has made the fishery vulnerable; hence, information on the current stock status is essential for the sustainability of the kingfish stock. Three length-based stock assessment approaches (TropFishR, spawning potential ratio, and Bayesian biomass method) were used to estimate growth, mortality, exploitation, spawning potential capacity, and relative biomass in relation to maximum sustainable yield (MSY). Asymptotic length (L_∞) was 186.31 cm, and the growth coefficient (K) was 0.15 yr⁻¹ for S. commerson. Fishing mortality was 0.45 yr⁻¹, which was higher than natural mortality (M = 0.18 yr⁻¹) and optimal fishing mortalities (F40% = 0.15 yr⁻¹). The exploitation rate (E) was found to be 0.71 yr⁻¹, higher than the optimum exploitation (E = 0.50), indicating a total overfishing of 42% of the S. commerson in Oman waters. The current length at first capture (Lc50 = 74.38 cm) was significantly smaller than the length at first maturity (Lm50 = 91.25 cm), indicating growth overfishing. The current spawning potential ratio (SPR) was 10%, which was significantly below the reference point (SPR = 20%), indicating that the stock was severely overfished. Biomass was critically low (B/Bo = 0.17), and lower than the reference point of 0.20. Additionally, the current biomass was 44% of Bmsy (B/Bmsy = 0.44), which is significantly lower than the reference point of 1, indicating that the stock biomass was below the maximum sustainable yield level, suggesting recruitment overfishing. Stock indicators revealed that the fishery was primarily targeting immature/juvenile fish, as well as older and larger fish, which indicated stocks were both growth- and recruitment-overfished. Therefore, carrying out commercial fishing for an optimum size range (118 to 144 cm) and reducing fishing pressure to a sustainable level (F = M, 0.18 ^yr−1) would sustain a healthy stock biomass of kingfish in Omani waters. Full article

(This article belongs to the Special Issue Sustainable Management of Small-Scale and Data-Limited Fisheries: Diagnosis and Strategies)

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17 pages, 1231 KB

Open AccessArticle

Functional Algal Feeds for Aquaculture: Micro- and Macroalgae Promote Gut Recovery in Gilthead Seabream

by Ibon García-Gallego, Cláudia Aragão, Rita Teodósio, Ana Teresa Gonçalves and Sofia Engrola

Fishes 2025, 10(11), 588; https://doi.org/10.3390/fishes10110588 - 15 Nov 2025

Viewed by 480

Abstract

Gut health is essential for optimal growth, immune function, and robustness in aquaculture. This study evaluated the potential of dietary supplementation with micro- and macroalgae to promote intestinal recovery following an insult. Four experimental diets were formulated for gilthead seabream (Sparus aurata [...] Read more.

Gut health is essential for optimal growth, immune function, and robustness in aquaculture. This study evaluated the potential of dietary supplementation with micro- and macroalgae to promote intestinal recovery following an insult. Four experimental diets were formulated for gilthead seabream (Sparus aurata) juveniles (176 ± 0.32 g): a control commercial-like diet (CTRL), and the same diet supplemented with either microalgae (Phaeodactylum tricornutum; PHA) or macroalgae (Gracilaria gracilis; GRA) at 2.5%, or a 5% blend of both (50:50; BLEND). To induce an intestinal insult, fish from each dietary group were assisted-fed with gelatine capsules containing soy saponins (CTRL + S, PHA, GRA, BLEND), while control fish received empty capsules (CTRL). After 72 h, CTRL and CTRL + S groups were fed the control diet, while PHA, GRA, and BLEND received their respective algae-supplemented diets. After 20 days, CTRL + S fish had significantly increased mucus cell numbers and submucosal cellular infiltration compared to CTRL fish, indicating intestinal disruption. PHA diet significantly upregulated igm, il10, and gpx. Fish fed GRA displayed a significant increase in mucosal vacuolation. BLEND diet showed synergistic effects, significantly upregulating il1b and pcna and reducing ALP activity. These results highlight the potential of combining micro- and macroalgae compounds to enhance gut recovery and immune activation. Full article

(This article belongs to the Special Issue Intestinal Health of Aquatic Organisms)

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17 pages, 4153 KB

Open AccessArticle

Transcriptomic Analysis of Largemouth Bass (Micropterus salmoides) Liver and Spleen Responses to Shewanella putrefaciens Infection

by Chongyu Zhong, Yijin Zhu, Xiangfeng Deng, Yuyan Sun, Yansong Zhang, Yujia Huo, Yueyue Fei and Min Wei

Fishes 2025, 10(11), 587; https://doi.org/10.3390/fishes10110587 - 14 Nov 2025

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Abstract

Shewanella putrefaciens is a significant bacterial pathogen causing high mortality in farmed largemouth bass (Micropterus salmoides). This study investigated the molecular immune responses in its primary target organs, the liver and spleen, via transcriptomic profiling at 24 h post-infection. We identified [...] Read more.

Shewanella putrefaciens is a significant bacterial pathogen causing high mortality in farmed largemouth bass (Micropterus salmoides). This study investigated the molecular immune responses in its primary target organs, the liver and spleen, via transcriptomic profiling at 24 h post-infection. We identified 458 significantly differentially expressed genes (DEGs) in the liver and 1405 in the spleen. Gene Ontology enrichment analysis revealed organ-specific immune strategies: the liver response was characterized by type I interferon signaling pathway, whereas the spleen response centered on the regulation of innate immune response. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that fatty acid metabolism and cytokine-cytokine receptor interaction were significantly enriched in the liver. In contrast, the C-type lectin receptor signaling pathway and cytokine-cytokine receptor interaction were the most prominent in the spleen. Several key DEGs (e.g., stat1a, rsad2, pglyrp5, pglyrp6, acaca, stat2, lepb) associated with immune response, metabolic adaptation, and cellular stress were identified, suggesting a coordinated host mechanism involving pathogen recognition, immunomodulation, and tissue repair. These results provide crucial insights into the immunomodulatory processes in largemouth bass against S. putrefaciens infection. Full article

(This article belongs to the Special Issue Molecular Design Breeding in Aquaculture)

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22 pages, 1944 KB

Open AccessArticle

Supplementation of Sage (Salvia officinalis) Essential Oil in Balanced Diets for Tropical Gar (Atractosteus tropicus) Larvae on Digestive and Antioxidant Enzyme Activities and Expression of Immune System Genes

by Yuliana Jiménez-León, Luis Daniel Jiménez-Martínez, Susana De La Rosa-García, Cesar Antonio Sepúlveda-Quiróz, Rafael Martínez-García, Graciela María Pérez-Jiménez, Otilio Méndez-Marín, Gloria Gertrudys Asencio-Alcudia and Carlos Alfonso Álvarez-González

Fishes 2025, 10(11), 586; https://doi.org/10.3390/fishes10110586 - 14 Nov 2025

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Abstract

The tropical gar (Atractosteus tropicus) has significant ecological, economic, and cultural importance in southeast Mexico, where aquaculture is increasing and fish are frequently exposed to stress. In this sense, feed additives such as sage (Salvia officinalis) strengthen organisms’ growth, [...] Read more.

The tropical gar (Atractosteus tropicus) has significant ecological, economic, and cultural importance in southeast Mexico, where aquaculture is increasing and fish are frequently exposed to stress. In this sense, feed additives such as sage (Salvia officinalis) strengthen organisms’ growth, immune systems, antioxidant capacities, and digestive capabilities. A 30-day experiment was conducted on larvae to determine the effect of different concentrations of sage essential oil (0%, 0.5%, 1%, 1.5%, and 2% treatments) supplemented in balanced diets. Significant differences (p < 0.05) between 0.5% and 2% sage oil supplement treatments for average weight were found. The highest acid and alkaline proteases, chymotrypsin, leucine aminopeptidase, amylase, and lipase activities were obtained for the sage oil-supplemented treatments. In contrast, trypsin showed the highest activity for treatment 0%, followed by diets with 0.5% and 2% sage oil. Regarding the antioxidant enzymatic activity for GPx, CAT and SOD, the highest activity was obtained in the diet with 1% sage oil, while in PEROx, the highest activity was recorded in the treatment with 0%, 1.5% and 2% S. officinalis supplementation. On the other hand, for relative gene expression, the highest expression was observed in sage-supplemented treatments for the nod, zo-1, zo-2, and occ genes. In contrast, the lowest expression was found in supplemented treatments for the il-10 and muc2 genes. These findings suggest that incorporating sage essential oil into the diets of tropical gar larvae, particularly at concentrations of 1.66% and 1.77%, holds potential for enhancing aquaculture practices for this important species. Full article

(This article belongs to the Special Issue Use of Essential Oils in Aquaculture)

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12 pages, 1045 KB

Open AccessArticle

Gene Expression and Antioxidant Characteristics of Rainbow Trout (Oncorhynchus mykiss) Eggs Used for Meiotic Gynogenesis

by Konrad Ocalewicz, Karolina Pałucha, Agata Błaszczyk, Marcin Kuciński, Stefan Dobosz, Ligia Panasiak and Rafał Rożyński

Fishes 2025, 10(11), 585; https://doi.org/10.3390/fishes10110585 - 13 Nov 2025

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Abstract

Gynogenesis is a reproductive mode where offspring inherit exclusively maternal chromosomes. Gynogenetic development in fish may be induced intentionally by activating eggs with the UV-irradiated, inactive spermatozoa. In the meiotic variant of gynogenesis, the resultant haploid gynogenetic zygote is then exposed to a [...] Read more.

Gynogenesis is a reproductive mode where offspring inherit exclusively maternal chromosomes. Gynogenetic development in fish may be induced intentionally by activating eggs with the UV-irradiated, inactive spermatozoa. In the meiotic variant of gynogenesis, the resultant haploid gynogenetic zygote is then exposed to a physical shock to inhibit the release of the 2nd polar body and to reconstitute the diploid state of the embryo. Here, meiotic gynogenesis was induced in the rainbow trout eggs from different clutches to find any differences in terms of gene expression and antioxidant enzyme activity between eggs with high and low ability for gynogenetic development. The survival rates of the gynogenotes after hatching from the eggs originating from five females varied from 16.6 ± 4.3% to 53.8 ± 9.8%. Biochemical and molecular examination revealed that eggs with higher developmental potential for meiotic gynogenesis exhibited significantly greater glutathione peroxidase (GPx) activity than eggs with lower efficiency of gynogenesis. Moreover, eggs exhibiting the highest ability for gynogenetic development showed increased transcription of the keratin 8 gene and decreased abundance of keratin 18 and tubulin β mRNA transcripts. Since keratins protect oocytes from physical stress after ovulation, the high abundance of keratin 8 in the rainbow trout eggs may increase their resilience to the physical shock applied for the zygote diploidization during gynogenesis. On the other hand, a low level of tubulin-building microtubules may increase the efficiency of high hydrostatic pressure (HHP) shock used for diploidization of the gynogenetic zygotes. Full article

(This article belongs to the Special Issue Genetics and Breeding of Fishes)

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17 pages, 6038 KB

Open AccessArticle

Impact of Hypoxia on Intestinal Health and Gut Microbiota in Anadara granosa

by Yueyue Li, Guangzhi Cheng, Jiaqi Jin, Yangguang Ji, Xiaolin Zhang, Yongbo Bao and Zhilan Peng

Fishes 2025, 10(11), 584; https://doi.org/10.3390/fishes10110584 - 13 Nov 2025

Viewed by 384

Abstract

Dissolved oxygen (DO) is a crucial determinant of aquatic organism health. This study demonstrates that hypoxia (at MH, 2.0 mg/L; SH, 0.5 mg/L) disrupts intestinal homeostasis in the blood clam, Anadara granosa. Exposure to hypoxia induced severe histopathological damage, including villus loss, [...] Read more.

Dissolved oxygen (DO) is a crucial determinant of aquatic organism health. This study demonstrates that hypoxia (at MH, 2.0 mg/L; SH, 0.5 mg/L) disrupts intestinal homeostasis in the blood clam, Anadara granosa. Exposure to hypoxia induced severe histopathological damage, including villus loss, inflammatory cell infiltration, and epithelial cell vacuolization. Immune-related gene expression analysis revealed coordinated regulation, with TLR4 and NF-κB significantly up-regulated by 4.5-fold and 5-fold, respectively, in the SH14 group, while HSP70 showed a remarkable 13-fold increase in the MH14 group. In contrast, TAK1 and TRAF6 exhibited substantial downregulation. High-throughput sequencing of the 16S rRNA gene revealed a significant reduction in gut microbiota diversity under hypoxic conditions, as evidenced by notable decreases of approximately 30% in the Chao1 index and 35% in the Shannon index in the SH group compared to the normoxic control (N group). Functional pathway analysis indicated alterations in pathways associated with xenobiotic biodegradation, lipid metabolism, and energy metabolism. These findings highlight a strong association between hypoxia and adverse intestinal health outcomes in A. granosa, underscoring the critical importance of maintaining adequate dissolved oxygen levels to support bivalve health. Future research should aim to develop strategies to mitigate hypoxia-induced stress and further elucidate the molecular mechanisms underlying hypoxia adaptation in bivalves. Full article

(This article belongs to the Section Physiology and Biochemistry)

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16 pages, 2715 KB

Open AccessArticle

Multi-Tissue Stable Isotope Analysis Reveals the Feeding Ecology of Dominant Shark Bycatch Species in the Northern South China Sea

by Kui Zhang, Pengli Xiong, Zuozhi Chen and Youwei Xu

Fishes 2025, 10(11), 583; https://doi.org/10.3390/fishes10110583 - 13 Nov 2025

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Abstract

Understanding the feeding mechanisms and interspecific coexistence of sharks is crucial for effective conservation. This study conducted stable isotope analysis on muscle and liver samples from 449 individuals of eight common bycatch shark species collected via bottom trawling in the northern South China [...] Read more.

Understanding the feeding mechanisms and interspecific coexistence of sharks is crucial for effective conservation. This study conducted stable isotope analysis on muscle and liver samples from 449 individuals of eight common bycatch shark species collected via bottom trawling in the northern South China Sea (NSCS). Results revealed significant differences in δ¹³C and δ¹⁵N values among species and tissue types. Scoliodon laticaudus exhibited the highest trophic position (TP_muscle = 4.60 ± 0.33; TP_liver = 4.53 ± 0.29), while Apristurus platyrhynchus had the lowest (TP_muscle = 2.97 ± 0.44; TP_liver = 2.75 ± 0.53). Muscle and liver isotopic signals were consistent, but δ¹³C differences indicated distinct carbon sources, with Carcharhinus sorrah linked to deep-sea organic matter and S. laticaudus to coastal inputs. Significant correlations between δ¹³C/δ¹⁵N and body length in A. platyrhynchus and Cephaloscyllium fasciatum suggest ontogenetic shifts in diet and habitat toward deeper waters. Trophic niche analysis using corrected standard ellipse area (SEAc) showed Halaelurus burgeri with the widest trophic niche (SEAc > 1.7‰²), reflecting a broad diet, while C. fasciatum had the narrowest (SEAc < 0.3‰²), indicating specialized feeding. Additionally, H. burgeri and C. sarawakensis exhibited significant niche differentiation, reducing interspecific competition, whereas C. fasciatum and Squalus megalops showed high niche overlap, suggesting intense resource competition. The narrower liver niche of C. sarawakensis may reflect recent habitat constriction due to bottom trawling. This study elucidates the feeding ecology and habitat resource utilization of NSCS sharks, providing a scientific basis for effective conservation strategies for shark populations in the region. Full article

(This article belongs to the Section Fishery Economics, Policy, and Management)

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17 pages, 6618 KB

Open AccessArticle

Transcriptome Analysis of Natural Albino Northern Snakehead (Channa argus var.) Provides Novel Insights into Color-Related Genes

by Yunbang Zhang, Qunxiang Ruan, Yiping Liu, Xin Wei, Ling Wang, Yunfei Chen, Jian Gao, Yuanchao Zou and Xiaojuan Cao

Fishes 2025, 10(11), 582; https://doi.org/10.3390/fishes10110582 - 13 Nov 2025

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Abstract

The northern snakehead (Channa argus) is an important economic fish species that holds a significant position in Chinese aquaculture due to its high nutritional value, fast growth, and anti-hypoxia capacity. There is a natural albino-mutant (AM) C. argus strain. Albinism, a [...] Read more.

The northern snakehead (Channa argus) is an important economic fish species that holds a significant position in Chinese aquaculture due to its high nutritional value, fast growth, and anti-hypoxia capacity. There is a natural albino-mutant (AM) C. argus strain. Albinism, a stable genetic trait characterized by loss of body pigmentation, provides a unique opportunity to study the molecular mechanisms of vertebrate coloration. This study investigates the molecular mechanisms underlying albinism in C. argus through skin transcriptomic analyses of wild type (WT) and AM individuals. Morphological and histological analysis revealed no significant phenotypic difference between WT and AM in early development, whereas adult AM exhibited a severe reduction in melanocytes. Through RNA sequencing of skin tissues from WT-adult, AM-adult, and AM-15dpf, a total of 10,891 differentially expressed genes (DEGs) were identified. Through DEG enrichment analyses, we identified a series of enriched pathways and genes related to albinism, including melanogenesis (i.e., tyr, tyrp1b, kitb, kitlga, pmela, pmelb, mitfa, and mitfb) and xanthophore formation (i.e., pax3a, pax3b, pax7a, and sox10). In conclusion, this study not only enriches the research on fish pigmentation, but also has potential significance for the aquaculture and breeding of C. argus. Full article

(This article belongs to the Section Genetics and Biotechnology)

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14 pages, 1197 KB

Open AccessArticle

Role of Hydrogen-Rich Water on Growth Performance and Liver Antioxidant Capacity of Mandarin Fish (Siniperca chuatsi)

by Haolin Wang, Jing Huang, Hua Liu, Ying Yang and Junru Hu

Fishes 2025, 10(11), 581; https://doi.org/10.3390/fishes10110581 - 12 Nov 2025

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Abstract

Hydrogen-rich water (HRW) is known for its antioxidant, anti-inflammatory, and growth-enhancing properties. However, research on its effects on mandarin fish (Siniperca chuatsi) is limited. This study aimed to explore the effects of HRW on the growth and liver antioxidant capacity of [...] Read more.

Hydrogen-rich water (HRW) is known for its antioxidant, anti-inflammatory, and growth-enhancing properties. However, research on its effects on mandarin fish (Siniperca chuatsi) is limited. This study aimed to explore the effects of HRW on the growth and liver antioxidant capacity of mandarin fish. A total of 3600 fish, with an initial average weight of 30 ± 1 g, were randomly divided into four groups (three replicates each) and treated with HRW for 0 h (control), 1 h, 2 h, and 3 h over an 8-week period. In this study, we found that HRW significantly enhanced weight gain, specific growth rate, and feed intake in mandarin fish, while reducing the feed conversion ratio. It also boosted antioxidant enzyme levels (SOD and GSH-PX) in the liver and lowered MDA. Additionally, HRW increased muscle growth-related gene expression (mrf4, myos, myod, mhc) and upregulated appetite-related genes (npy and agrp) while decreasing leptin levels. This study reveals that a hydrogen concentration of 200–320 ppb, especially with a 2 h HRW treatment, produces the most significant antioxidant effects in juvenile mandarin fish, while a 3 h treatment notably enhances growth. These findings offer valuable insights and support for the advancement of the mandarin fish breeding industry. Full article

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26 pages, 1522 KB

Open AccessArticle

Evaluation of Silymarin–L-Carnitine as a Dietary Supplement on Growth Performance, Antioxidants and Immunity, Gut/Liver Health, and Gene Expression in Nile Tilapia (Oreochromis niloticus)

by Akram Ismael Shehata, Eslam Tefal, Ayaat M. Elmaghraby, Asem A. Amer, Islam I. Teiba, Mayada Alhoshy, Mahmoud S. Gewaily, Zhixun Guo, Shengkang Li and Mohammed F. El Basuini

Fishes 2025, 10(11), 580; https://doi.org/10.3390/fishes10110580 - 11 Nov 2025

Viewed by 469

Abstract

Silymarin and L-carnitine are individually used in fish diets, yet whether they exert interactive or additive effects when combined remains unclear. This study aimed to investigate the individual and combined impacts of dietary silymarin (S), L-carnitine (LC), and their combination (S + LC) [...] Read more.

Silymarin and L-carnitine are individually used in fish diets, yet whether they exert interactive or additive effects when combined remains unclear. This study aimed to investigate the individual and combined impacts of dietary silymarin (S), L-carnitine (LC), and their combination (S + LC) on growth performance, digestive enzyme activity, antioxidant status, immune response, and gene expression in Nile tilapia. A total of 360 fish (initial body weight: 10.01 ± 0.03 g) were randomly allocated into 12 fiberglass tanks (30 fish/tank) and fed one of four diets for 84 days: control (basal diet), S (850 mg/kg), LC (500 mg/kg), and S + LC (425 mg/kg S + 250 mg/kg LC). Fish fed S and S + LC diets exhibited significantly higher final body weight, weight gain, and specific growth rate (SGR), along with improved feed conversion ratio (FCR) compared to the control (p < 0.05). All supplemented groups exhibited enhanced digestive enzyme activities (amylase, lipase, protease), with the S + LC group showing the highest values. Serum biochemical profiles revealed increased total protein and globulin and reduced glucose and cortisol levels. Innate immune responses (IgM, lysozyme activity, NBT%, and bactericidal activity) were significantly elevated, especially in the S + LC group. Antioxidant enzyme activities (SOD, CAT, GPx) increased, while malondialdehyde (MDA) levels declined. Gene expression analysis showed significant upregulation of IGF-1, IFNA-1, SOD, CAT, and Gsr, with the greatest expression in the S + LC group. These findings indicate that dietary silymarin and L-carnitine, particularly when provided together, produced complementary and enhanced effects on growth, immune competence, antioxidant capacity, and gene regulation in Nile tilapia. Full article

(This article belongs to the Special Issue Therapeutic Potential of Probiotics, Prebiotics, and Synbiotics in Advancing Aquaculture Health and Performance)

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20 pages, 2264 KB

Open AccessCommunication

Strategies for Broodstock Farming in Arid Environments: Rearing Juvenile Seriola lalandi in a Low-Cost RAS

by Renzo Pepe-Victoriano, Piera Pepe-Vargas, Elizabeth Borquez-Segovia, Jordan I. Huanacuni, Héctor Aravena-Ambrosetti, Felipe Méndez-Abarca, Juan Zenón Resurrección-Huertas and Luis Antonio Espinoza-Ramos

Fishes 2025, 10(11), 579; https://doi.org/10.3390/fishes10110579 - 10 Nov 2025

Viewed by 472

Abstract

This study evaluated the feasibility of culturing Seriola lalandi in a low-cost recirculating aquaculture system (RAS) in an arid region of northern Chile, aiming to establish strategies for broodstock farming and diversify national aquaculture. The system was designed as a low-cost recirculating aquaculture [...] Read more.

This study evaluated the feasibility of culturing Seriola lalandi in a low-cost recirculating aquaculture system (RAS) in an arid region of northern Chile, aiming to establish strategies for broodstock farming and diversify national aquaculture. The system was designed as a low-cost recirculating aquaculture system (RAS) built with locally available materials, such as galvanized corrugated steel panels and flexible plastic liners, instead of specialized aquaculture tanks. Its modular configuration, based on gravity-fed filtration using sedimentation, sand, and disc filters, allows efficient water reuse with minimal energy consumption and a daily water turnover of 12 times the total volume. This design significantly reduced construction and operational costs, making it a feasible option for aquaculture development in arid regions with limited water resources. Over an 8-month period, 46 S. lalandi individuals were used, and the results showed successful physiological adaptation of the specimens to confinement, as evidenced by low mortality, progressive acceptance of formulated feed, and sustained growth. Individual weights progressively increased, with averages ranging from 675 to 1435 g, and the specific growth rate (SGR) fluctuated between 0.14 and 0.43% per day. Fulton’s condition factor (K) remained in an adequate range between 2.4 and 2.8, suggesting good physical condition of the sampled individuals. Water quality within the RAS system was maintained within acceptable parameters, although a strong negative correlation between temperature and dissolved oxygen was recorded (Spearman coefficient = −0.71, p < 0.001), highlighting the importance of monitoring these factors in warm environments. The lack of adequate protocols for the adaptation of marine species in arid areas, such as northern Chile, has limited aquaculture development in these regions. This study addresses this problem by assessing the feasibility of a low-cost recirculating system (RAS) for the cultivation of S. lalandi under conditions of water scarcity, with the aim of diversifying the national aquaculture in arid zones. Full article

(This article belongs to the Section Sustainable Aquaculture)

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14 pages, 2777 KB

Open AccessArticle

Genomic Structure and Hybridization Patterns of Brown Trout (Salmo trutta L.) in the Aosta Valley Using ddRAD-seq, mtDNA-CR, and LDH-C1* Markers

by Edo D’Agaro, Pierpaolo Gibertoni and Stefano Esposito

Fishes 2025, 10(11), 578; https://doi.org/10.3390/fishes10110578 - 10 Nov 2025

Viewed by 247

Abstract

The aim of this research was to characterize the genetic structure of brown trout species complex populations in nine river basins in the Aosta Valley and neighbouring regions in northern Italy. We used a combined analysis of nuclear lactate dehydrogenase (LDH-C1*), [...] Read more.

The aim of this research was to characterize the genetic structure of brown trout species complex populations in nine river basins in the Aosta Valley and neighbouring regions in northern Italy. We used a combined analysis of nuclear lactate dehydrogenase (LDH-C1*), mitochondrial DNA-CR (control region) (mtDNA-CR) sequences and ddRAD-seq-generated single-nucleotide polymorphism. In this way, we estimated the degree of hybridization of wild populations with the Atlantic-derived hatchery lineage. The results of the genetic analyses showed a complex genetic structure with different levels of introgression at the respective sampling sites. The mitochondrial lineages (Atlantic (AT), Mediterranean (ME), Adriatic (AD), and Marmoratus (MA)) were present with varying percentages across the sampling sites. Data analysis using the Admixture v.1.3.0 software allowed the identification of four distinctive cluster units in the Aosta Valley. For the Vertosan River, we identified a distinct native population and a level of hybridization close to zero. In terms of conservation, this population with a distinct native lineage represents a high priority for protection and serves as a reservoir for the entire western north Italian alpine zone. Some interventions to support conservation actions within the study area can be envisaged. Full article

(This article belongs to the Special Issue Conservation and Population Genetics of Fishes)

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19 pages, 2376 KB

Open AccessArticle

Evaluation of Nutritional Value of the First Generation (G1) of Population Breeding of Eriocheir sinensis “King Crab 1”

by Dandan Gao, Gaowei Zhang, Yongchun Ge, Xinhai Wang, Chun Wu and Xuanpeng Wang

Fishes 2025, 10(11), 577; https://doi.org/10.3390/fishes10110577 - 10 Nov 2025

Viewed by 349

Abstract

The nutritional composition of commercially valuable crabs is governed by a complex interplay of hereditary factors, growth environment, developmental stage and feed composition. In this study, the nutritional characteristics of edible tissues were quantitatively compared among four populations of Eriocheir sinensis: a [...] Read more.

The nutritional composition of commercially valuable crabs is governed by a complex interplay of hereditary factors, growth environment, developmental stage and feed composition. In this study, the nutritional characteristics of edible tissues were quantitatively compared among four populations of Eriocheir sinensis: a non-selected group (NF), the G1 generation of the selective bred “King Crab 1” group (SF), the SF group with water quality regulated using microbiological agents (SF8) and a chilled-fish feeding group (CF). Growth metric analysis revealed that females in the SF group exhibited slightly superior growth performance compared to other groups. Amino acid analysis demonstrated that compared to the NF group, the content of essential and umami amino acids in the ovary was remarkably increased in the SF8 group. Additionally, the SF and CF groups exhibited elevated contents of flavor amino acids in male crabs. Moreover, the CF group exhibited the highest contents of EPA and DHA, and the highest n-3/n-6 PUFAs ratio, with the SF group following. Overall, although the G1 generation of selectively bred crabs demonstrated improved nutritional indicators compared to the unselected group, they still lagged behind the CF group in several aspects. These findings provide valuable insights and data support for future breeding strategies. Full article

(This article belongs to the Section Nutrition and Feeding)

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17 pages, 2133 KB

Open AccessArticle

Modeling the Water Source Ecosystem in the Middle Route of the South-to-North Water Diversion Project: Implications for Management and Conservation

by Geng Huang, Ting Yuan, Huan Lei, Chao Guo, Zetao Chen, Mantang Xiong, Chenguang Li, Wei Chen, Lequn Zhang, Yuqi Wang and Feng Chen

Fishes 2025, 10(11), 576; https://doi.org/10.3390/fishes10110576 - 10 Nov 2025

Viewed by 334

Abstract

The Danjiangkou Reservoir (DJKR) serves as the water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), yet comprehensive understanding of its ecosystem structure and function remains limited. This study addressed this knowledge limitation by developing an Ecopath model with [...] Read more.

The Danjiangkou Reservoir (DJKR) serves as the water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), yet comprehensive understanding of its ecosystem structure and function remains limited. This study addressed this knowledge limitation by developing an Ecopath model with 22 functional groups, parameterized using field survey data from 2022 to 2023. Our findings revealed a trophic structure spanning levels 1 to 3.59, with the highest level occupied by piscivorous mandarin fish (Siniperca spp.). Energy flowed through two dominant pathways, with the grazing food chain demonstrating higher transfer efficiency compared to the detrital pathway. Mixed trophic impact analysis identified the introduced icefish (Neosalanx taihuensis) as exerting substantial negative impacts on most functional groups. Key ecosystem indices, including the total primary production to total respiration ratio (TPP/TR, 1.99), connectance index (CI, 0.248), and system omnivory index (SOI, 0.113), collectively indicated an ecosystem of moderate maturity and stability. Persistent challenges include the proliferation of N. taihuensis, suboptimal energy transfer between trophic levels III and IV, and inefficient utilization of primary productivity. To enhance ecosystem resilience and maintain water quality, we recommend the targeted removal of icefish and strategic management of zooplanktivorous fish populations. Full article

(This article belongs to the Section Biology and Ecology)

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18 pages, 2640 KB

Open AccessArticle

Full-Length Transcriptome Characterization and Molecular Analysis of the Longfin Batfish (Platax teira)

by Lingeng Lv, Baosuo Liu, Huayang Guo, Kecheng Zhu, Nan Zhang, Jinhui Sun and Dianchang Zhang

Fishes 2025, 10(11), 575; https://doi.org/10.3390/fishes10110575 - 8 Nov 2025

Viewed by 253

Abstract

Platax teira is a marine fish species with both ornamental and economic value, but it faces challenges in aquaculture due to environmental stress and disease. Genetic research on P. teira has been limited due to the limitations of the partially incomplete reference genome [...] Read more.

Platax teira is a marine fish species with both ornamental and economic value, but it faces challenges in aquaculture due to environmental stress and disease. Genetic research on P. teira has been limited due to the limitations of the partially incomplete reference genome and the lack of a complete transcriptome. In this study, we utilized PacBio SMRT sequencing to generate a full-length transcriptome for P. teira, obtaining 39,770 isoforms, including 32,265 known gene-related transcripts and 4730 novel transcripts from 3455 new genes. All novel genes were annotated, and enrichment analysis revealed significant associations between immune-related pathways, such as cAMP, MAPK, PI3K-Akt, and Wnt. We also identified 14,398 alternative splicing events, 2754 alternative polyadenylation events, 42,250 SSRs, 1569 transcription factors, and 2067 long non-coding RNAs. Additionally, protein–protein interaction (PPI) analysis of immune-related pathways predicted chemokines as key immune factors among novel genes. Domain prediction analysis highlighted the diverse functional potential of immune factors such as NLRC3, tyrosine kinase 2, and A2M in different alternative splicing events. Overall, the characterization of the full-length transcriptome dataset of P. teira lays the foundation for further studies on its genetic analysis and immune regulation. Full article

(This article belongs to the Special Issue Molecular Genetics and Genomics of Marine Fishes)

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13 pages, 1538 KB

Open AccessArticle

The Differences in the Responses of Pelagic Fish Distribution in the Northern South China Sea to Environmental Factors: A Case Study of Round Scad and Jack Mackerel in the Hainan Island Offshore Area

by Liangming Wang, Binbin Shan, Changping Yang, Yan Liu and Dianrong Sun

Fishes 2025, 10(11), 574; https://doi.org/10.3390/fishes10110574 - 7 Nov 2025

Viewed by 341

Abstract

Round scad (Decapterus maruadsi) and jack mackerel (Trachurus japonicus) are economically significant pelagic species widely distributed in the northern South China Sea (SCS), with overlapping habitats and life history stages. To examine the distribution patterns of round scad and [...] Read more.

Round scad (Decapterus maruadsi) and jack mackerel (Trachurus japonicus) are economically significant pelagic species widely distributed in the northern South China Sea (SCS), with overlapping habitats and life history stages. To examine the distribution patterns of round scad and jack mackerel and their responses to environmental variables, we conducted a preliminary analysis using catch and environmental data from four seasonal surveys around Hainan Island. Three species distribution models—generalized linear models (GLM), generalized additive models (GAM), and random forests (RF)—were applied to quantify species–environment relationships. Explanatory variables included both biotic and abiotic factors: temperature, salinity, water depth, sea surface chlorophyll a concentration (SSC), phytoplankton abundance, and zooplankton abundance. The results revealed pronounced spatial heterogeneity in the high-density areas of both species. Among the models, GAM consistently explained a higher proportion of deviance in the observed distributions. Further analysis showed that round scad and jack mackerel responded differently to environmental gradients such as water depth and temperature, although their responses to varying plankton concentrations were largely consistent. Specifically, round scad are typically found in waters at depths ranging from 0 to 50 m, whereas jack mackerel tend to inhabit depths exceeding 100 m. In response to high plankton abundance, both species exhibit a notable increase in resource availability when plankton levels surpass 3. These findings indicate distinct spatial niches and suggest potential competition in feeding ecology between the two species. Overall, the study enhances understanding of the spatial dynamics of key commercial species in the northern SCS and provides valuable insights for sustainable fisheries management and conservation planning. Full article

(This article belongs to the Special Issue Sustainable Fisheries Dynamics)

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33 pages, 5100 KB

Open AccessArticle

Impact of Effective Probiotic Microorganisms (EPMs) on Growth Performance, Hematobiochemical Panel, Immuno-Antioxidant Status, and Gut Cultivable Microbiota in Striped Catfish (Pangasianodon hypophthalmus)

by Mahmoud Abdullah Elnakeeb, Ahmed Mohamed Ashry, Ahmed Mohamed El-Zayat, Abdel Wahab Abdel-Moez Abdel-Warith, Mahmoud Mohamed Habiba, Elsayed Mohamed Ibrahim Younis, Simon John Davies, Ibrahim Mohamed Ibrahim, Fatma Elzhraa and Ahmed Mohammed El-Sebaey

Fishes 2025, 10(11), 573; https://doi.org/10.3390/fishes10110573 - 7 Nov 2025

Viewed by 651

Abstract

Striped catfish, Pangasianodon hypophthalmus, has recently emerged as a promising candidate for Egyptian aquaculture owing to its rapid growth; however, under intensive culture, it is vulnerable to Aeromonas hydrophila. The efficacy of dietary supplementation with effective probiotic microorganisms (EPMs) in enhancing [...] Read more.

Striped catfish, Pangasianodon hypophthalmus, has recently emerged as a promising candidate for Egyptian aquaculture owing to its rapid growth; however, under intensive culture, it is vulnerable to Aeromonas hydrophila. The efficacy of dietary supplementation with effective probiotic microorganisms (EPMs) in enhancing growth performance, feed utilization, physiological health, and disease resistance of P. hypophthalmus against A. hydrophila challenge was evaluated. A 90-day feeding trial was conducted with 300 fish randomly distributed into four triplicate groups (25 fish per replicate) reared in 12 indoor fiberglass tanks: a control and three groups receiving EPMs at inclusion levels of 1.5%, 3%, and 4.5%. The results showed significant, dose-dependent improvements across all EPMs-supplemented groups in survival, growth rates, feed utilization, and hematological parameters (RBC, Hb, PCV, WBC, and lymphocytes). Dietary EPMs led to significant improvements (p ≤ 0.001) in digestive efficiency, protein and lipid metabolism, antioxidant enzyme activity, immune performance, and the ability of striped catfish to withstand A. hydrophila infection. Hepatobiliary enzyme activities (ALT, AST, and ALKP), glucose levels, lipid profile markers, and hepatic MDA exhibited a significant linear decrease (p ≤ 0.0001) with increasing EPMs levels. The gut microbial composition showed a dose-dependent increase in beneficial lactic acid bacteria (LAB) and a reduction in TAPC, pathogenic coliforms (TFCC), and Vibrio spp. (TVC). These results demonstrate the dose-dependent effects of EPMs on enhancing aquafeed efficiency, overall health, and innate immunity in striped catfish. Full article

(This article belongs to the Special Issue Effect of Dietary Supplementation on the Growth and Immunity of Fish and Shellfish—3rd Edition)

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17 pages, 3213 KB

Open AccessArticle

Metabolic Responses and Oxidative Stress Adaptation Mechanisms of the Pituitary Gland in the Tiger Puffer Under Low-Temperature Stress

by Yifan Li, Taicheng Li, Meihui Yao, Chuan Li, Zibin Jiang, Hongyu Pan, Wei Wang, Yajuan Li and He Zhou

Fishes 2025, 10(11), 572; https://doi.org/10.3390/fishes10110572 - 7 Nov 2025

Viewed by 398

Abstract

To explore the induction of low temperature the Tiger Puffer (Takifugu rubripes) In this study, the influence of temperature on the pituitary gland during masculinization was investigated through chronic hypothermia stress experiments. Metabolomics was used to analyze the metabolic regulatory network [...] Read more.

To explore the induction of low temperature the Tiger Puffer (Takifugu rubripes) In this study, the influence of temperature on the pituitary gland during masculinization was investigated through chronic hypothermia stress experiments. Metabolomics was used to analyze the metabolic regulatory network of the pituitary gland under hypothermia stress. ELISA technology was employed to determine the activity content of oxidative stress-related enzymes in the pituitary gland. Further, TUNEL fluorescence labeling and qPCR were used to detect the apoptosis level of pituitary cells. Finally, to assess the impact of low-temperature stress on muscle tissue, HE staining and qPCR techniques were employed. The results showed that after 45 days of low-temperature stress, the differential metabolites of the pituitary gland were mainly enriched in the amino acid metabolic signaling pathway, and the contents of amino acids such as GSH and its synthetic precursors in the pituitary tissue changed significantly. The contents of oxidative stress indicators such as ROS and MDA all showed a trend of first increasing and then decreasing. The qPCR results of TUNEL fluorescence labeling and apoptosis-related genes were consistent, indicating that the apoptotic level of pituitary cells first increased and then decreased with the stress process. Histological analysis revealed that low temperature led to muscle cell atrophy and increased interstitial space in muscle tissue. The expression changes in genes related to muscle development further confirmed that low temperature significantly inhibited muscle growth and development. Therefore, this study speculates that after being subjected to chronic low-temperature stress, the pituitary gland of the red-finned Oriental pufferfish can alleviate the oxidative stress response of the body by strengthening the amino acid metabolic pathway, and the fish body has shown a physiological trend of gradually adapting to low-temperature stress, but the growth and development of muscles are still significantly inhibited. The results of this study can provide theoretical support for understanding the physiological adaptation mechanism of the red-finned Oriental pufferfish to low-temperature stress and lay a foundation for subsequent in-depth exploration of the pituitary response mechanism to low temperatures. Full article

(This article belongs to the Special Issue Environmental Physiology of Aquatic Animals)

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16 pages, 3930 KB

Open AccessArticle

Impact of Ocean Acidification on the Intestinal Microflora of Sinonovacula constricta

by Yuan Wei, Hesheng Dou, Chengju Chai, Tingkuan Wang, Huiru Liu, Shuang Liang, Yongren Li, Jian Liang and Yongjun Guo

Fishes 2025, 10(11), 571; https://doi.org/10.3390/fishes10110571 - 7 Nov 2025

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Abstract

The intestinal microflora, which is vital for nutrient absorption and immune regulation, can experience dysbiosis under environmental stress, potentially enhancing host susceptibility to pathogenic invasion. The impact of ocean acidification on bivalves is substantial, but its effects on their intestinal microflora remain poorly [...] Read more.

The intestinal microflora, which is vital for nutrient absorption and immune regulation, can experience dysbiosis under environmental stress, potentially enhancing host susceptibility to pathogenic invasion. The impact of ocean acidification on bivalves is substantial, but its effects on their intestinal microflora remain poorly understood. To explore the impact of ocean acidification on the intestinal microflora of Sinonovacula constricta, this study used high-throughput 16S rRNA sequencing technology to investigate the variations in the intestinal microflora communities of S. constricta during ocean acidification across different time points. After exposure to ocean acidification, changes in the composition of the intestinal microflora of S. constricta were observed, with no significant difference in α-diversity between the acidified and control groups. The abundance of Proteobacteria in the acidification group increased, whereas that of Cyanobacteria decreased. The abundance of Firmicutes initially decreased and then increased. At the genus level, the relative abundance of Pseudomonas was lower than that in the control group, whereas the relative abundance of Photobacterium, Acinetobacter, and Enterobacter gradually increased. LEfSe analysis identified Serpens as the discriminative biomarker at 7 days of acidification, Enterobacteriales, Rhodobacteraceae, and Martvita at 14 days of acidification, and Serpens, Acidibacteria, and Aeromonadaceae at 35 days of acidification. Functional prediction analysis indicated significant stimulation in various metabolic pathways at different time points following acidification stress. Specifically, pathways involved in biosynthesis were significantly stimulated at 14 days of acidification, while those related to sucrose degradation were disrupted at 35 days. The results further indicated that ocean acidification stress can influence the intestinal microflora of S. constricta, but no severe dysbiosis or digestive system impairment was observed at the microbial level. This study provides new insights into the effects of ocean acidification on the intestinal microflora of marine bivalves. Full article

(This article belongs to the Section Aquatic Invertebrates)

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12 pages, 3504 KB

Open AccessArticle

Full-Length Transcriptome Reveals Heterologous Sperm Fragments in Natural Gynogenetic Grass Carp

by Lang Qin, Yuxiang Wang, Ming Wen, Jinhui Huang, Xu Huang, Qian Chen, Dan Peng, Yang Wu, Qianye Wei, Fangzhou Hu, Kaijun Gong, Chun Zhang, Qinbo Qin, Chang Wu and Shaojun Liu

Fishes 2025, 10(11), 570; https://doi.org/10.3390/fishes10110570 - 7 Nov 2025

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Abstract

Grass carp (Ctenopharyngodon idella) is one of the most economically important cyprinid species cultured in China. The diploid gynogenetic grass carp (2nGGC, 2n = 48) was generated from the hybrid of female grass carp (GC, 2n = 48) and male topmouth [...] Read more.

Grass carp (Ctenopharyngodon idella) is one of the most economically important cyprinid species cultured in China. The diploid gynogenetic grass carp (2nGGC, 2n = 48) was generated from the hybrid of female grass carp (GC, 2n = 48) and male topmouth culter (TC, 2n = 48, Culter alburnus). This study obtained the full-length transcriptome of 2nGGC from five tissues using Pacific Biosciences (Pacbio) single-molecule real-time long-read isoform sequencing. Following the mapping of long reads to GC and TC reference genomes, a total of 1848 fusion isoforms were identified. Among them, 775 were distributed across different genomes, indicating that chimeric DNA fragments of TC were embedded in the 2nGGC genome. After removing the fusion genes and redundant isoforms, 107,721 full-length transcripts were obtained from 2nGGC, providing important full-length reference sequences for further research. Finally, comparative analysis of homologous gene variation identified 34 fragments in 2nGGC containing recombinant SNPs derived from both GC and TC. These results provide evidence that natural gynogenesis represents a form of “micro-hybridization” characterized by heterogeneous DNA fragments, distinct from traditional hybridization involving chromosome-level recombination. These findings offer valuable reference for fish genetic breeding. Full article

(This article belongs to the Special Issue Genetics and Breeding of Fishes)

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12 pages, 230 KB

Open AccessArticle

An Evaluation of Chlorella (Chlorella pyrenoidosa) in the Feed of Juvenile Tiger Puffer (Takifugu rubripes)

by Jiahao Liu, Qingyan Gao, Chenchen Bian, Qiang Ma, Yuliang Wei, Mengqing Liang and Houguo Xu

Fishes 2025, 10(11), 569; https://doi.org/10.3390/fishes10110569 - 6 Nov 2025

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Abstract

Microalgal protein demonstrates considerable potential for reducing dependence on fishmeal in aquafeeds. However, limited research has been conducted on the effects of Chlorella pyrenoidosa meal (CM) on carnivorous fish species. This study evaluated the impact of replacing 0% to 40% of fishmeal with [...] Read more.

Microalgal protein demonstrates considerable potential for reducing dependence on fishmeal in aquafeeds. However, limited research has been conducted on the effects of Chlorella pyrenoidosa meal (CM) on carnivorous fish species. This study evaluated the impact of replacing 0% to 40% of fishmeal with CM within isonitrogenous and isolipidic diets (designated as CM0, CM5, CM10, CM20, and CM40) on juvenile tiger puffer (initial weight: 11.34 ± 0.01 g) over a 56-day feeding trial. Three replicate tanks were established for each experimental group, with 30 fish per tank. The experimental data were statistically analyzed using one-way analysis of variance (ANOVA) and regression analysis. The results showed that no significant differences were observed in final body weight (FBW: CM0, 55.45 ± 1.87 g; CM40, 45.6 ± 2.09 g) or specific growth rate (SGR: CM0, 2.83 ± 0.06%/d; CM40, 2.48 ± 0.08%/d) among the dietary groups; however, the growth linearly decreased with increasing CM levels. The CM40 group exhibited a significantly higher feed conversion ratio (FCR: CM0, 1.17 ± 0.02; CM40, 1.28 ± 0.03). Muscle texture parameters (hardness, adhesiveness, cohesiveness, springiness, gumminess, and chewiness) and proximate composition were not significantly affected by dietary treatments. In contrast, the CM40 diet significantly decreased the n-3/n-6 polyunsaturated fatty acid (PUFA) ratio in the muscle, while increasing the contents of 18:2n-6 and total n-6 PUFAs. These results indicate that substituting up to 5% of fishmeal with CM did not produce significant adverse effects on growth or body composition, although linear trends indicated a progressive decline in performance at higher inclusion levels. This investigation provides valuable insights into the application of sustainable protein alternatives in feeds for marine carnivorous fish. Full article

(This article belongs to the Special Issue Development of Low-Crop, Low-Fishmeal or Low-Fish Oil Feeds for Aquaculture)

13 pages, 1556 KB

Open AccessArticle

Potential Hierarchical Interactions of Megafauna Species at a Cleaning Station

by Yotam Barr and Avigdor Abelson

Fishes 2025, 10(11), 568; https://doi.org/10.3390/fishes10110568 - 6 Nov 2025

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Abstract

Cleaning stations on seamounts play a crucial ecological role in the health and behavior of marine megafauna, yet interspecific interactions at these sites remain understudied. This study investigates potential hierarchical dynamics between reef manta rays (Mobula alfredi) and pelagic thresher sharks [...] Read more.

Cleaning stations on seamounts play a crucial ecological role in the health and behavior of marine megafauna, yet interspecific interactions at these sites remain understudied. This study investigates potential hierarchical dynamics between reef manta rays (Mobula alfredi) and pelagic thresher sharks (Alopias pelagicus) at two cleaning stations atop a seamount in the Philippines. Using over 960 h of autonomous video recordings across 119 survey days, we examined species-specific site preferences, visitation types, and behavioral responses to interspecific encounters. Results indicate that, while manta rays used both stations equally, thresher sharks showed a strong preference for the deeper, sloped station. Interruptions during cleaning suggest a hierarchy: all manta-to-shark interactions resulted in thresher sharks vacating the station prematurely, possibly before completing cleaning. In contrast, manta–manta interactions showed more balanced outcomes, with no significant impact on cleaning duration. Shark presence decreased as the flow speed intensified and was lowest during high tide, suggesting that sharks’ decision to clean may be dictated by factors affecting the effectiveness of the cleaning process. These findings also suggest that manta rays may outcompete thresher sharks for access to cleaning services. Understanding such interspecific dynamics is vital for effective marine habitat management and the conservation of vulnerable pelagic species. Full article

(This article belongs to the Section Biology and Ecology)

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Open AccessArticle

β,β-Dimethylacrylshikonin Alleviates Zebrafish (Danio rerio) Soyasaponin-Induced Enteritis by Maintaining Intestinal Homeostasis and Improving Intestinal Immunity and Metabolism

by Ming Liu, Xin Lu, Leong-Seng Lim, Yinhui Peng, Lulu Liu, Kianann Tan, Peng Xu, Mingzhong Liang, Yingrui Wu, Qingfang Gong and Xiaohui Cai

Fishes 2025, 10(11), 567; https://doi.org/10.3390/fishes10110567 - 6 Nov 2025

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Abstract

Soyasaponin intolerance is common in ancient fish species, making them susceptible to enteritis caused by dietary soybean meal. β,β-Dimethylacrylshikonin is the key active monomer found in Lithospermum erythrorhizon and is known for its multiple pharmacological activities. However, its effect on soybean meal-induced enteritis [...] Read more.

Soyasaponin intolerance is common in ancient fish species, making them susceptible to enteritis caused by dietary soybean meal. β,β-Dimethylacrylshikonin is the key active monomer found in Lithospermum erythrorhizon and is known for its multiple pharmacological activities. However, its effect on soybean meal-induced enteritis remains unknown. The administration of 2 g/kg of β,β-Dimethylacrylshikonin (LE) effectively alleviated 5 g/kg of soyasaponin-induced histopathological changes and dysfunction, as evidenced by the expression of inflammation-related genes (il-1β, il-8, and il10). Regarding the gut microbiota composition, LE therapy decreased the population of inflammation-linked Proteobacteria and concurrently elevated the proportion of Fusobacteriota, effectively sustaining the balance of the zebrafish gut microbiota. Moreover, at the genus level, LE treatment also increased the abundance of Cetobacterium. Transcriptional results suggested that LE intervention mainly regulated immune-related pathways, including cytokine–cytokine receptor interaction, the TGF-beta signaling pathway, taurine and hypotaurine metabolism, and arachidonic acid metabolism. In conclusion, 5 g/kg of soyasaponins caused intestinal injury in zebrafish, and β,β-Dimethylacrylshikonin can reduce intestinal inflammation by regulating the intestinal microbial balance and metabolic disorder, with the best effect at 2 g/kg. Full article

(This article belongs to the Special Issue Genetic Breeding and Immunity of Aquatic Animals)

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Fishes, Volume 10, Issue 11 (November 2025) – 62 articles

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